// Command vellum is the unified media server: one process, one database,
// every media type.
package main

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/mithral/vellum/internal/auth"
	"github.com/mithral/vellum/internal/catalog"
	"github.com/mithral/vellum/internal/cli"
	"github.com/mithral/vellum/internal/core"
	"github.com/mithral/vellum/internal/discovery"
	"github.com/mithral/vellum/internal/home"
	"github.com/mithral/vellum/internal/httpapi"
	"github.com/mithral/vellum/internal/jellyfin"
	"github.com/mithral/vellum/internal/jobs"
	"github.com/mithral/vellum/internal/library"
	"github.com/mithral/vellum/internal/media"
	"github.com/mithral/vellum/internal/metadata"
	"github.com/mithral/vellum/internal/modules/comics"
	"github.com/mithral/vellum/internal/modules/ebooks"
	"github.com/mithral/vellum/internal/modules/games"
	_ "github.com/mithral/vellum/internal/modules/photos" // registers the thumbnail extractor
	"github.com/mithral/vellum/internal/playback"
	"github.com/mithral/vellum/internal/providers"
	"github.com/mithral/vellum/internal/scanner"
	"github.com/mithral/vellum/internal/search"
	"github.com/mithral/vellum/internal/subsonic"
	"github.com/mithral/vellum/migrations"
)

// version is overridden at build time with -ldflags "-X main.version=...".
var version = "dev"

func main() {
	cfg, err := core.LoadConfig()
	if err != nil {
		fmt.Fprintln(os.Stderr, "vellum: fatal:", err)
		os.Exit(1)
	}
	log := core.NewLogger(cfg.LogLevel, cfg.LogFormat)

	// Administrative subcommands run instead of the server. This is the way
	// back in when someone is locked out, and the way to take a backup while
	// the server is stopped.
	if handled, err := cli.Run(os.Args[1:], cfg, log); handled {
		if err != nil {
			fmt.Fprintln(os.Stderr, "vellum:", err)
			os.Exit(1)
		}
		return
	}

	if err := run(cfg, log); err != nil {
		fmt.Fprintln(os.Stderr, "vellum: fatal:", err)
		os.Exit(1)
	}
}

func run(cfg core.Config, log *slog.Logger) error {
	log.Info("starting vellum", "version", version, "listen", cfg.Listen)

	if err := cfg.Validate(); err != nil {
		return err
	}

	db, err := core.OpenDB(cfg.DBPath)
	if err != nil {
		return err
	}
	defer db.Close()

	migCtx, cancelMig := context.WithTimeout(context.Background(), 60*time.Second)
	err = core.Migrate(migCtx, db, migrations.FS, log)
	cancelMig()
	if err != nil {
		return err
	}

	api := httpapi.New(db, log, version)

	authenticator := auth.NewAuthenticator(db, cfg.CookieName, cfg.SessionTTL, cfg.CookieSecure, log)
	authenticator.TrustedProxies = cfg.TrustedProxies
	if !cfg.CookieSecure {
		log.Warn("VELLUM_COOKIE_SECURE is false; session cookies will be sent over plain HTTP. " +
			"Set it to true when serving over TLS.")
	}

	if err := auth.EnsureAdminFromEnv(context.Background(), db, log, cfg.AdminUser, cfg.AdminPassword); err != nil {
		return fmt.Errorf("bootstrap admin: %w", err)
	}

	authHandlers := auth.NewHandlers(authenticator, log)
	authHandlers.Register(api.Mux())
	api.SetAuth(authenticator)

	// Background work: a table-backed queue in the same database. Created
	// before the modules so a module's handlers can enqueue work.
	queue := jobs.New(db, log)

	library.NewHandlers(db, log, authenticator, queue).Register(api.Mux())
	media.NewHandlers(db, log, authenticator, cfg.ConfigDir).Register(api.Mux())
	// The landing screen is an aggregate over items, not an item resource, so it
	// is mounted by its own package.
	home.NewHandlers(db, log, authenticator).Register(api.Mux())
	ebooks.NewHandlers(db, log, authenticator).Register(api.Mux())
	comics.NewHandlers(db, log, authenticator).Register(api.Mux())
	games.NewHandlers(db, log, authenticator).Register(api.Mux())
	search.NewHandlers(db, log, authenticator).Register(api.Mux())
	// Playback engine registry + selection. Vellum never transcodes, so the
	// server reports what is inside a file and matches it against the engines the
	// CLIENT declares — a browser offers "html5", a native client can offer mpv.
	playback.NewHandlers(catalog.New(db), log, authenticator).Register(api.Mux())

	// Client compatibility layers. Neither speaks the session cookie; both
	// authenticate with an api_tokens credential and then go through the same
	// grant chokepoint as the web app. They mount at the root because that is
	// where the real clients look, and both report SupportsTranscoding=false:
	// this server has no CPU for it, so a client that demands a transcode is
	// refused rather than left waiting for one that will never start.
	jellyfin.NewHandlers(db, log, authenticator).Register(api.Mux())
	subsonic.NewHandlers(db, log, authenticator).Register(api.Mux())

	// Scans run on the queue rather than inside the request: a real library
	// takes longer than any sensible timeout, and a hanging request is
	// indistinguishable from a broken server. The result is written back so
	// the UI can read progress.
	queue.Register(library.ScanJobKind, func(ctx context.Context, payload json.RawMessage) error {
		var p library.ScanPayload
		if err := json.Unmarshal(payload, &p); err != nil {
			return fmt.Errorf("scan: bad payload: %w", err)
		}
		lib, err := library.Get(ctx, db, p.LibraryID)
		if err != nil {
			return nil // deleted since the job was queued
		}
		res, err := scanner.Scan(ctx, db, lib, log)
		if jobID, ok := jobs.JobID(ctx); ok {
			if serr := jobs.SetResult(ctx, db, jobID, res); serr != nil {
				log.Warn("record scan result", "err", serr)
			}
		}
		return err
	})

	// Providers are registered primary-first; a fallback is only consulted
	// when the primary returns nothing.
	providers.Register(providers.NewOpenLibrary())
	providers.Register(providers.NewGoogleBooks())
	providers.Register(providers.NewMusicBrainz())
	if cfg.ComicVineAPIKey != "" {
		providers.Register(providers.NewComicVine(cfg.ComicVineAPIKey))
	} else {
		log.Info("comic metadata disabled: set VELLUM_COMICVINE_API_KEY to enable ComicVine lookups")
	}
	if cfg.IGDBClientID != "" && cfg.IGDBClientSecret != "" {
		providers.Register(providers.NewIGDB(cfg.IGDBClientID, cfg.IGDBClientSecret))
	} else {
		log.Info("game metadata disabled: set VELLUM_IGDB_CLIENT_ID and VELLUM_IGDB_CLIENT_SECRET to enable IGDB lookups")
	}
	if cfg.TMDBAPIKey != "" {
		providers.Register(providers.NewTMDB(cfg.TMDBAPIKey))
	} else {
		log.Info("video metadata disabled: set VELLUM_TMDB_API_KEY to enable TMDB movie and TV lookups")
	}
	if cfg.TPDBAPIKey != "" {
		providers.Register(providers.NewThePornDB(cfg.TPDBAPIKey))
	} else {
		log.Info("adult metadata disabled: set VELLUM_TPDB_API_KEY to enable ThePornDB lookups")
	}
	enricher := metadata.NewEnricher(db, log, cfg.ConfigDir)
	queue.Register(metadata.JobKind, enricher.Handle)
	metadata.NewHandlers(db, log, authenticator, queue).Register(api.Mux())

	// Anything left 'running' belongs to a previous process that died mid-job.
	// Requeue before the workers start, or it stays 'running' forever and the
	// UI polls a job that will never move.
	if n, err := queue.RecoverStale(context.Background()); err != nil {
		log.Warn("recover stale jobs", "err", err)
	} else if n > 0 {
		log.Info("requeued jobs left running by a previous process", "count", n)
	}

	jobCtx, cancelJobs := context.WithCancel(context.Background())
	defer cancelJobs()
	go queue.Run(jobCtx)

	// mDNS: advertise on the LAN so clients browse to this server instead of
	// being handed a URL. Cancelled with the job queue so the records are
	// withdrawn before the process exits.
	kinds := make([]string, 0)
	for _, mt := range library.SupportedTypes() {
		kinds = append(kinds, mt.Kind)
	}
	go discovery.Start(jobCtx, cfg, version, kinds, log)

	srv := &http.Server{
		Addr:    cfg.Listen,
		Handler: api.Handler(),
		// ReadHeaderTimeout protects against slowloris. WriteTimeout is
		// deliberately zero: streaming large media files must not be cut off.
		ReadHeaderTimeout: 10 * time.Second,
		ReadTimeout:       cfg.ReadTimeout,
		WriteTimeout:      cfg.WriteTimeout,
		IdleTimeout:       cfg.IdleTimeout,
		ErrorLog:          nil,
	}

	errCh := make(chan error, 1)
	go func() {
		log.Info("listening", "addr", cfg.Listen, "data_dir", cfg.DataDir)
		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			errCh <- err
		}
	}()

	stop := make(chan os.Signal, 1)
	signal.Notify(stop, os.Interrupt, syscall.SIGTERM)

	select {
	case err := <-errCh:
		return fmt.Errorf("http server: %w", err)
	case sig := <-stop:
		log.Info("shutting down", "signal", sig.String())
	}

	shutdownCtx, cancel := context.WithTimeout(context.Background(), cfg.ShutdownGrace)
	defer cancel()
	if err := srv.Shutdown(shutdownCtx); err != nil {
		return fmt.Errorf("graceful shutdown: %w", err)
	}
	cancelJobs()
	log.Info("stopped")
	return nil
}